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Xref: sserve comp.arch:28001 comp.unix.bsd:7632 comp.os.linux:15152 Newsgroups: comp.arch,comp.unix.bsd,comp.os.linux Path: sserve!manuel.anu.edu.au!munnari.oz.au!uunet!zaphod.mps.ohio-state.edu!usc!cs.utexas.edu!sun-barr!sh.wide!kogwy!math-keio!mad From: mad@math.keio.ac.jp (MAEDA Atusi) Subject: Re: IDE faster than Mips SCSI disk In-Reply-To: eoahmad@ntuix.ntu.ac.sg's message of Fri, 6 Nov 1992 03: 39:42 GMT Message-ID: <MAD.92Nov7220823@amber.math.keio.ac.jp> Lines: 54 Sender: news@math.keio.ac.jp Nntp-Posting-Host: amber Reply-To: mad@math.keio.ac.jp Organization: Faculty of Sci. and Tech., Keio Univ., Yokohama, Japan. References: <1992Nov6.033942.21194@ntuix.ntu.ac.sg> Date: Sat, 7 Nov 1992 13:08:26 GMT In article <1992Nov6.033942.21194@ntuix.ntu.ac.sg> eoahmad@ntuix.ntu.ac.sg (Othman Ahmad) writes: > IDE is just a simple interface definition, just like SCSI-2, but IDE, >is optimised for HARD DISKS, SCSI is not. SCSI is more general purpose. You may be right. But unfortunately, bare speed of hard disk drives around is not so fast (typically < 2MB/sec) that can fill up the bandwidth. And, as Dan Hildebrand mentioned (in article <7j+q=2d@quantum.on.ca>), SCSI can do multiple transfer at the same time, as well as let CPU free from data transfer job and keep computing. You can't even perform seek on another IDE drive during IDE data transfer. It can make a difference under multi-tasking OS. >This PC machine runs on 386bsd. Using 1 megabyte test file it is faster than >a similar 486/50Mhz EISA SCSI-2 hard-disk. > >486/33 Maxtor 7120 200Mbyte [deleted] >IOZONE performance measurements: > 367586 bytes/second for writing the file > 499942 bytes/second for reading the file The PC result looks reasonable. But mips result seem to be too slow for SCSI-2 disks. Maybe because (as Phillip Fayers written in <13481.9211061131@thor.cf.ac.uk>) poor I/O performance of Ultrix. But I think larger buffer size (e.g. 8192 bytes) would be better for testing disk drive/interface performance, while smaller buffer size test can measure total I/O performance including OS/library overhead. On SparcStation1+ with SCSI drive, running SunOS 4.1.1, I get: 32M file, 512bytes buffer: IOZONE performance measurements: 204348 bytes/second for writing the file 556120 bytes/second for reading the file 32M file, 8192bytes buffer: IOZONE performance measurements: 653760 bytes/second for writing the file 1207012 bytes/second for reading the file Hmm... SunOs, too, seems to have significant overhead with small buffers. Is this figure mean ISA machine running 386bsd beats SparcStation1+ in I/O? PCs are widely believed to be "comparable to WS in CPU speed, but far more slower in I/O". I'm very interested in the result of EISA SCSI-2 with large file size & large buffer size, if it's available. ;;; Keio University ;;; Faculty of Science and Technology ;;; Department of Math ;;; MAEDA Atusi (In Japan we write our family names first.) ;;; mad@math.keio.ac.jp